1. Field of the Invention
The present invention relates to an NBT-BT crystal piezoelectric film and a piezoelectric stacking structure comprising the same.
2. Description of the Related Art
Perovskite composite oxide [(Na, Bi)1-xBax]TiO3 (hereinafter, referred to as “NBT-BT”) has been recently researched and developed as a non-lead (lead-free) ferroelectric material.
US Pre-Grant Patent Application Publication No. 20130328974A1 discloses an NBT-BT film having a high polarization-disappearance temperature Td. Specifically, US Pre-Grant Patent Application Publication No. 20130328974A1 discloses that a (1-α) (Na, Bi, Ba)TiO3-αBiQO3 (Q=Fe, Co, Zn0.5Ti0.5, or Mg0.5Ti0.5) layer formed on an NaxLa1-x+yNi1−yO3, layer by an RF magnetron sputtering under a temperature of 650 degrees Celsius has a polarization-disappearance temperature Td of approximately 180 degrees Celsius to 250 degrees Celsius. The (1-α) (Na, Bi, Ba)TiO3-αBiQO3 layer has a (001) orientation only. The NaxLa1-x+yNi1−yO3-x layer is formed on a Pt film having orientation (111) by an RF magnetron sputtering under a temperature of 300 degrees Celsius.
U.S. Pat. No. 7,965,021, U.S. Pat. No. 8,562,113, and U.S. Pat. No. 8,511,162 disclose an NBT-BT film having a (001) orientation only. The NBT-BT film disclosed in these documents is formed on a LaNiO3 layer. The LaNiO3 layer is formed by an RF magnetron sputtering under a temperature of 300 degrees Celsius. It is well known that a LaNiO3 layer has an intense (001) orientation.
U.S. Pat. No. 8,393,719 also discloses an NBT-BT film having a (001) orientation only. The NBT-BT film disclosed in U.S. Pat. No. 8,393,719 is formed on an NaxLa1-xNiO3 (0.01≦x≦0.1) layer. Similarly to the disclosures of U.S. Pat. No. 7,965,021, U.S. Pat. No. 8,562,113, and U.S. Pat. No. 8,511,162, the NaxLa1-xNiO3 layer is also formed by an RF magnetron sputtering under a temperature of 300 degrees Celsius. The NaxLa1-xNiO3 layer also has an intense (001) orientation.
US Pre-Grant Patent Application Publication No. 20130038666A1 also discloses an NBT-BT film having a (001) orientation only. The NBT-BT film disclosed in US Pre-Grant Patent Application Publication No. 20130038666A1 is formed on a Pt layer having a (100) orientation. The Pt layer is formed on a surface of an MgO monocrystalline substrate having a (100) orientation. None of these documents discloses a polarization-disappearance temperature Td.
Journal of the American Ceramic Society 93 [4] (2010) 1108-1113 discloses a method for measuring a polarization-disappearance temperature Td.